Kemi Badenoch insisted Labour MPs must do the right thing today as she called for a sleaze probe into Keir Starmer's Mandelson chaos.

The Tory leader warned that the Commons needs to show that 'rules matter' as she kicked off a debate that could decide the PM's fate. 

Mrs Badenoch said the Labour benches would not be forgiven if they were 'complicit in a cover-up' by blocking a privileges committee probe into whether the House was misled. 

As Westminster builds up to the critical vote this evening, Sir Keir has been rocked by more evidence from key players in the appointment of Peter Mandelson as US ambassador. 

The former head of the Foreign Office told MPs that No10 had exerted pressure to push through the peer's security clearance. Philip Barton also suggested normal process had not been followed because the appointment was announced before Mandelson had been through vetting.

Sir Keir previously told Parliament that 'full due process' was followed over Mandelson's appointment, and flatly denied any pressure was put on the Foreign Office. 

In another dramatic session at the foreign affairs committee, Sir Keir's ex-chief of staff Morgan McSweeney tried to save his erstwhile boss by taking responsibility for the disastrous choice of envoy.

Mr McSweeney said Sir Keir 'relied on my advice and I got it wrong'. But he also admitted that No10 had been aware of the 'pros and cons' of appointing Mandelson, who had long-standing ties to Jeffrey Epstein.

Downing Street has been using every lever at its disposal to stop Labour MPs rebelling in a the vote this evening. 

Whips have been warning that those who fail to back Sir Keir could be kicked out of the party, with ministers frantically ringing round to woo waverers.

In the Commons, Mrs Badenoch said: 'The Ministerial Code is very clear: ministers who mislead the House must correct the record, and I quote 'at the earliest opportunity'.

'It is very obvious that … what the Prime Minister said at the despatch box was not correct. It's clear that full due process was not followed. If Labour MPs allow the whips to force them to block the consequences of these decisions, it will degrade not just them, but this House.

'The question is, what kind of people are they? Are they people who will live up to the promises they made about standards and the rules mattering, or are they people who abandon their promises to be complicit in a cover-up?'

Describing the debate as a 'stunt' is 'disrespecting this House and disrespecting the Speaker', Mrs Badenoch said, adding: 'It's very obvious they've all been told to come here today. Tell everybody it's a stunt, tell everybody it's a stunt.

'Why are they acting like sheep? Why are they acting like sheep? They should be better than that.'

Appearing before the foreign affairs committee, Mr McSweeney stressed he had not tried to sidestep the vetting process for the US ambassador job. 

The dramatic comments came hours before Sir Keir faces a make-or-break showdown in the Commons over whether he misled MPs. 

Mr McSweeney said he believed Mandelson was the best choice because Britain was 'exposed' on trade after Brexit and with Donald Trump in the White House. 

He acknowledged that the New Labour architect had been a 'confidante' - but denied he was a 'mentor'. 

'What I did do was make a recommendation based on my judgment that (Mandelson's) experience, relationships and political skills could serve the national interest in Washington at an important moment. That judgment was a mistake,' Mr McSweeney said.

'What I did not do was oversee national security vetting, ask officials to ignore procedures, request that steps should be skipped, or communicate, explicitly or implicitly, the checks should be cleared at all costs. 

'I would never have considered that acceptable. These processes are in place to protect our national security.'

Earlier, Sir Philip Barton told MPs that the Cabinet Office initially argued the peer was a 'fit and proper person' and did not need to go through 'developed vetting'.

Sir Philip also revealed that he was not consulted about Mandelson's appointment as US ambassador in advance, and was merely told the PM had 'accepted the risks and decided to proceed'.

He said there was 'pressure' from the centre of Government to push the process through so that Mandelson could be in Washington within a month.

Sir Philip said that was an 'ambitious timetable' and there would have been a 'crisis' if the peer had been rejected after being publicly announced, signed off by the King and accepted by the US administration.

'The normal order is vetting then announcement,' he said. 'The timing of the announcement was driven and decided by No10.'

Mr McSweeney said: 'The appointment of Mandelson as ambassador was a serious error of judgment. I advised the Prime Minister in support of that appointment, and I was wrong to do so.

'As I said in my resignation statement, I resigned because I believe responsibility should rest with those who make serious mistakes. Accountability in public life cannot apply only when it is convenient. The Prime Minister relied on my advice, and I got it wrong.

Challenged on his reliance on advice from Mandelson, Mr McSweeney said: 'He was a confidant for me. I didn't regard him as my mentor.

'I first had a conversation with Peter Mandelson in 2017. I don't think I really started to go to him for advice until about 2021, and I was 44 years of age then, so I didn't regard him at all as a mentor.

'I got advice from him, and it was useful, but I also had other people around who were perhaps a bit more shy with the media, who I saw too for advice. I was working with… we brought in some extremely experienced people from the Blair administration.

'So Liz Lloyd came into our team, Jonathan Powell came into our team, and I would certainly ask both of those for advice about how things work as well. So I asked a range of people for advice and help. I don't regard Mandelson as ever being a mentor, but certainly as an adviser.'

Mr McSweeney said the PM had been presented with a choice of either Mandelson or Tory former Chancellor George Osborne as the US envoy.

'I said to the PM you have two appointable candidates,' the ex-aide said. 

McSweeney said he learned details of Mandelson's relationship with Epstein through the release of files related to the paedophile financier over the course of 2025.

He described the revelations as 'like a knife through my soul'.

'The nature of the relationship that I understood he had with Epstein was not a close friendship. How I understood it at the time was a passing acquaintance that he regretted having and that he apologised for,' he said.

'What has emerged since then was way, way, way worse than I had expected at the time, and it was when I saw the pictures, when I saw the Bloomberg questions in September 2025, I have to say it was like a knife through my soul.'

Mr McSweeney insisted that if Mandelson had failed vetting he would not have been appointed. 

'If it had happened, we'd have withdrawn the ambassadorship. It would have been a political embarrassment,' he said. 

Mr McSweeney suggested Downing Street would have gone on to ask Karen Pierce to stay on for longer as ambassador.

The Labour strategist admitted it would have been 'much better' if he the Cabinet Office propriety and ethics team had posed questions to Lord Mandelson about his links to Epstein.

Instead he chose to make inquiries in writing - with No10 now saying Mandelson did not give a full picture. 

'I think that when I look back on it, I certainly think it would have been much, much better if I'd asked Pet to ask those follow-up questions,' Mr McSweeney said.

'I guess my thinking at the time was I'd put follow-up questions to him in writing, and that if a senior member of staff did that, that he would feel more obligated to give the truth and the full truth.'

Former Foreign Office chief Olly Robbins revealed in his evidence to MPs last week that conversations took place about giving an ambassadorial job to Sir Keir's outgoing spin doctor Lord Doyle.

Asked about the discussions, Mr McSweeney said: 'It was clear that Matthew Doyle's time in Government was coming to an end, and the Prime Minister wanted me as part of that, to discuss with Matthew Doyle next steps, because these are difficult conversations. And the Prime Minister wanted me to convey to him that if he had wanted to stay in Government, that he should consider doing so because he had extensive experience in Government.

'The private office asked what vacancies that Matthew Doyle might apply for. There was no suggestion at any point that he would be imposed in. If he had wanted to work in the Foreign Office, Matthew Doyle would have had to apply for any of those posts the same as anybody else.'

Mr McSweeney said then-foreign secretary David Lammy was not told about the discussions as Lord Doyle's exit from Government at the time was a 'delicate HR issue'.

Earlier, Sir Philip said he was 'presented with a decision... and told to get on with it'.  

The evidence appears to contradict suggestions from the Cabinet Office that it had insisted on DV for the peer. 

Sir Keir has been going all-out to save his skin as he faces a Commons test later that could decide his fate.

Defeat for the PM would trigger a formal inquiry by the privileges committee, throwing his floundering government deeper into a tailspin.

Sir Philip told the committee: 'As we were taking forward the practical steps required, the Cabinet Office initially said that as Mandelson was to use the technical phrase from the guidance a ''fit and proper person'', as a member of the House and Lords, he did not require developed vetting.

'I mean, to be honest with you, I thought that was odd and insufficient. I had been deputy ambassador in Washington, and therefore occasionally charge-d'affaires. I knew very well to do the job effectively, you have to be party to some of the deepest secrets that the UK Government holds.

'But I also recognise that the situation was unusual, and I therefore asked for advice, although it was pretty clear in my mind from the FCDO security team. They came back to me after discussions with the Cabinet Office, and said that their advice was that he should have DV, and I absolutely agreed with that.'

Sir Philip said by that time the Cabinet Office had also 'reflected' and agreed that DV was needed. 

Sir Philip said he only learned the Government wanted to appoint Lord Mandelson to the post on December 15, 2024.

Sir Keir had been 'made aware of the risks, and had accepted those risks and decided to proceed', Sir Philip added.

Sir Philip denied an extraordinary claim aired before the committee last week, that Mr McSweeney told him to 'just f***ing approve' the appointment in a phone call.

But he made clear there was 'pressure' from No10 - something Sir Keir has flatly denied. 

'There's two possible questions here. Question one is, was there pressure on the substance of the DV case?' he said.

'Question two is, was there pressure to get the DV case done in a particular timeframe?'

He continued: 'Answer one is, during my tenure, I was not aware of any pressure on the substance of the Mandelson DV case.

'Question two, was there pressure? Absolutely.'

He added: 'I don't think anyone could have been in any doubt in the department working on this that there was pressure to get everything done as quickly as possible.'

Challenged whether No10 had been dismissive of the DV process, Sir Philip said: 'I wouldn't use the word dismissive. The word I would use is uninterested. I think people wanted to know that all the practical steps required for Mandelson to arrive in Washington on or around the inauguration date. It needed to be completed at pace, as it were.' 

Sir Philip said there was no contingency plan for what would happen if Mandelson's DV had been refused, although he stressed it could have caused a crisis.

'It would have been a crisis if we got to the point where he had no vetting clearance, that would have been a crisis,' he said.

He added that 'a publicly-announced political appointment as the next ambassador to Washington not being able to go, that would have been a big problem'.

The mandarin said he personally had concerns about the peer's appointment due to his long-standing friendship with paedophile financier Jeffrey Epstein. 

'There was no space for dialogue,' Sir Philip told the MPs. 'I had a concern that a man who demonstrably from the public record at the time – and it was clearly much bigger than we all knew – had a link to Epstein, and that Epstein through both the presidential election campaign in the US and more generally in US politics, had been and was a controversial figure, and I was worried that this could become a problem in future…

'That is a very candid account of probably what I was thinking at the time, but there was no space or avenue or mechanism for me to put that on the table.

'A decision had been taken. It was a political decision.'

The intervention came with a major arm-twisting operation in full effect at Westminster, with a three-line whip in place for Labour MPs to support the Government.

That is in stark contrast to when Sir Keir called a similar vote against Boris Johnson over Partygate. At that point he argued that MPs should be free to follow their own consciences. 

Writing in the Daily Mail today, Kemi Badenoch said MPs of all stripes have a duty to hold Sir Keir to account for treating Parliament with 'contempt'.

She told Labour backbenchers they are 'not in the Commons simply to protect the PM from embarrassment'.

'Labour MPs now face a test of their own,' the Tory leader said.

'They can circle the wagons, obey the Whips and tell themselves this is just politics. Or they can remember they are MPs before they are members of the Labour Party.'

Allies of Sir Keir are confident they can hold restive Labour MPs at bay, with crucial local elections barely a week away.

The PM told a packed meeting of the Parliamentary Labour Party last night: 'When we stick together and fight together we are so much stronger.'

He sought to dismiss the Commons vote as a 'stunt' ahead of the May elections.

'I have responsibility for being totally transparent with you, with Parliament and the British public,' he said.

'I take that very seriously as well. But this is not about a lack of transparency.

'This is a political stunt by our opponents who want to bring us down, obscure our message, stop us getting on with our work.

'And the timing tells you everything, nine days before local elections.'

He said the Conservatives had put forward 'totally baseless' and 'absolutely ridiculous' accusations against him and insisted the motion on Tuesday was 'pure politics', adding: 'We need to stand together against it.'

The Privileges Committee was responsible for Mr Johnson's exit from frontline politics after it investigated him for misleading the House over the 'Partygate' breaches of Covid laws in Downing Street.

He quit as an MP in 2023 before the committee published a report recommending his suspension.

The Government also took the unusual step last night of publishing a letter from former cabinet secretary Sir Chris Wormald to the PM, in which he said he had concluded the 'appropriate processes were followed' in both the appointment and sacking of the peer.

Sir Keir has also faced questions for insisting to MPs that 'no pressure existed whatsoever in relation to this case' after former top Foreign Office official Sir Olly Robbins said there had been 'constant chasing' from No 10 while checks were taking place for the ambassadorship.

Sir Olly's claims were echoed in written evidence to the Foreign Affairs Committee published last night from another key figure in the security process.

According to a letter from the Foreign Office drafted in consultation with Ian Collard, who was head of security in the department, the official said he 'felt pressure to deliver a rapid outcome' to the clearance procedure.

This was in light of 'regular contact from No 10 to the FCDO (permanent under-secretary's) office,' the letter said, although Mr Collard did not personally speak to Downing Street colleagues and 'does not assess that this pressure influenced professional judgment that was reached by himself or his team'.

The PM has been accused of misleading MPs by saying 'full due process' was followed in appointing Lord Mandelson, who was given developed vetting status despite failing security checks.

The Foreign Office, under then top civil servant Sir Olly, cleared him despite red flags raised by experts at the UK Security Vetting (UKSV) agency.

Mr Collard, who briefed Sir Olly on the vetting findings, also did not see the UKSV file recommending clearance be denied, according to the letter published on Monday.

Instead, he received an oral briefing from officials which led him to believe Lord Mandelson's case was 'borderline' and that 'the risks could be mitigated,' the evidence said.

She said: 'The Prime Minister misled the House of Commons repeatedly. He appointed a national security risk and friend of a convicted paedophile to be our ambassador in Washington, our most sensitive diplomatic post'

Mr Brown urged Labour to unite in focusing on putting 'the needs of the country first' in a statement.

'Whatever the parliamentary games at Westminster, what the country expects of everyone in Labour is to focus on the priorities of the British people, which is what Keir Starmer is doing and for which he deserves all our support,' he said.